An olefin polymerization catalyst consisting of a vanadium compound having three ligands such as .beta.-diketone, etc. coordinated and an organoaluminum compound, in combination, is well known.
On the other hand, a titanium compound or zirconium compound each having two lignads coordinated is known, but it has not been reported that such a compound has a polymerization capacity of olefins.
The principal object of the present invention is to provide an olefin polymerization catalyst comprising, as a component, a transition metal compound having two ligands such as .beta.-diketone, etc. coordinated.
The inventors have made various studies and consequently, have found that the object of the present invention can be attained by combination of the transition metal compound with an organoaluminum compound, in particular, aluminoxane. The present invention is based on this finding. Disclosure of the Invention
Accordingly, the gist of the present invention consists in an olefin polymerization catalyst comprising:
(a) a transition metal compound represented by the general formula, ##STR2## wherein M represents titanium, zirconium, hafnium or vandium, Y.sup.1 and Y.sup.2 each represent, same or different, halogen atoms or alkyl groups containing 1 to 10 carbon atoms and R.sup.1, R.sup.2 and R.sup.3 each represent hydrogen atoms or hydrocarbon groups containing 1 to 10 carbon atoms, at least one of which is a hydrogen atom but all of which must not be hydrogen atoms, and
(b) an organoaluminum compound. Best Embodiment for practicing the Invention